A float web dryer conventionally comprises an enclosure having an entrance and exit and through which a traveling web to be dried is transported while supported or floated via upwardly ejected air jets which support the web free from mechanical contact while traveling through the dryer.
The enclosure may be formed by upper and lower chambers which can be opened from each other if this is required to thread the start of the web through the dryer. Threading may require not only opening of the two chambers, but a reduction in the air jet force, and usually the use of highly trained operators.
In the paper industry such a dryer can be provided with a threading device in the form of chains which can be used by the operators to engage one edge portion of the paper web so as to carry the start of the web through the dryer to a driven pulling drum about which the web is then wrapped to pull the web through the dryer.
In other fields the web may be composed of relatively loose fibers so that the web is unable to resist substantial tensioning or pulling forces when applied locally to the web. An example of such a web is one that is in the form of a matting of fibers such as fiberglass matting. In such cases the web can be torn apart by treatment which might be satisfactory when threading a float dryer with a paper web.
One solution is to provide the float dryer with a transport screen which carries at least the starting end of the fibrous web through the float dryer. However, loose fibrous material forming a matted web is usually impregnated with an adhesive treatment substance applied in a more or less liquid phase and which is why the web requires drying. Such a substance sticks to a transport screen and ultimately requires the screen to be cleaned in one way or another and involving substantial servicing expense.
The object of the present invention is to provide an apparatus for threading such a fibrous material web through a float dryer without requiring opening of the dryer's chambers, the use of expert operating personnel or expensive servicing of the apparatus.